The present invention relates to an electric machine excited by permanent magnets, and more particularly to such a machine in which the stator comprises a yoke frame forming the magnetic return with permanent magnets being secured to the inside of the yoke frame.
In German Auslegeschrift No. 1 160 080 is disclosed a machine in which flat magnet slabs, on which pole pieces are placed for concentrating the magnetic flux, are fastened to a yoke frame of angular inside and outside shape. The pole pieces project toward the rotor of the machine and are rounded at least partially to correspond to the diameter of the rotor. These pole pieces must be made in a separate operation and also must be assembled subsequently in the stator of the machine.